The present invention relates to an ignition system for internal combustion engines.
More particularly, it relates to a circuit arrangement for ignition systems for detecting an arc voltage at a spark plug, which voltage is transformed onto a primary side of an ignition coil.
An ignition system is already known from U.S. Pat. No. 4,918,389 or from the corresponding EP-A-0,344,349, and in this the monitoring of the ignition system is carried out by means of a primary-side monitoring of the spark duration. The disadvantage of this method, however, is that it does not give exact information on the combustion trend, in order thereby to draw conclusions as to the functioning of the ignition system and/or injection system. Malfunctions therefore cannot be detected reliably, and because of this an increased exchange of harmful substances can occur and the catalyst be put at risk.
To satisfy the exhaust-gas value requirements of the environmental authorities, the aim is to develop ignition controls which guarantee the least possible ejection of harmful substances in four-stroke petrol engines.
One possibility of ignition and explosion detection is afforded by means of a pressure sensor or optical sensor. However, such function monitoring by the sensors additionally incorporated in the ignition system entails high cost.